230V AC/DC ground ... again.

[Baggywrinkle]

Attached is the plan for my 230V AC install, which I posted on the Victron FB Community for an appraisal and it has generated some debate around AC grounding as the Victron published schematics and installation instructions for the MultiPlus II seem to contradict the advice of an ABYC certified installer. My system plan is attached.

The question is, do I rely on all the internal AC earth connections in the Multiplus to the chassis/case and the 50mm2 main ground cable (which is labelled PE in the manual) for my AC earthing, or do I need a separate AC ground bus bar external to the Multiplus?

In both cases the AC and DC grounds are connected together and both go to the hull grounding point which has an anode on the seawater side. (My boat is GRP).

I probed the Multiplus with a multi-meter and all the PE inputs and outputs on the AC connectors are directly connected to the DC main ground on the case.

Discussion on the Victron community web site here .... Primary Gnd connection for ?

 

[PaulRainbow]

Attached is the plan for my 230V AC install, which I posted on the Victron FB Community for an appraisal and it has generated some debate around AC grounding as the Victron published schematics and installation instructions for the MultiPlus II seem to contradict the advice of an ABYC certified installer. My system plan is attached.

The question is, do I rely on all the internal AC earth connections in the Multiplus to the chassis/case and the 50mm2 main ground cable (which is labelled PE in the manual) for my AC earthing, or do I need a separate AC ground bus bar external to the Multiplus?

In both cases the AC and DC grounds are connected together and both go to the hull grounding point which has an anode on the seawater side. (My boat is GRP).

I probed the Multiplus with a multi-meter and all the PE inputs and outputs on the AC connectors are directly connected to the DC main ground on the case.

Discussion on the Victron community web site here .... Primary Gnd connection for ?

AC in, and outs are, as you found, internally bonded to one another and the case. The case has to be grounded "to the water", to ensure a ground connection should you unplug from shore power.

So if you're wired as per your second picture and the case PE is connected to the anode, that's all you need.

 

[jakew009]

Attached is the plan for my 230V AC install, which I posted on the Victron FB Community for an appraisal and it has generated some debate around AC grounding as the Victron published schematics and installation instructions for the MultiPlus II seem to contradict the advice of an ABYC certified installer. My system plan is attached.

The question is, do I rely on all the internal AC earth connections in the Multiplus to the chassis/case and the 50mm2 main ground cable (which is labelled PE in the manual) for my AC earthing, or do I need a separate AC ground bus bar external to the Multiplus?

In both cases the AC and DC grounds are connected together and both go to the hull grounding point which has an anode on the seawater side. (My boat is GRP).

I probed the Multiplus with a multi-meter and all the PE inputs and outputs on the AC connectors are directly connected to the DC main ground on the case.

Discussion on the Victron community web site here .... Primary Gnd connection for ?

View attachment 204447

View attachment 204467

I assume your ‘common ground’ is essentially your DC negative busbar and then you have a connection from that to an anode?

I did it slightly differently in that my link from the AC earth to the anode was taken from the consumer unit rather than the DC bus bar but I don’t think that makes any difference.

As I understand it the reason the case earth has to be 50mm2 (or the same size as whatever your main DC positive feed is), is that if the DC positive shorts out to the case the case earth has to be able to handle that current. If you don’t fit the massive case earth cable, the fault current tries to find its way back via the mains cables inevitably melting them.

 

[sealutions]

You must have an earth to neutral link in order for your RCDs to work correctly. The multiplus has an internal ground relay which handles this for you so long as you make sure that the internal ground relay is turned ON (which is should be by default).